Piston skirt expander



Allg- 8, 1933- v c. w. PRocHAsKA l,921 ;429

PISTON SKIRT EXPANDER Filed May 6. 1952 2 Sheets-Sheet l XNVENTOR ATTO R N EYS Aug. 8, 1933.. c. w. PRocHAsKA 1,921,429

- PIsToN SKIRT EXPANDER Filed May 6, 1932 2 Sheets-Sheet 2y INVENTOR ATTORNEYS Patented Aug. 8, 1933 UNITED STATES PATENT vOFFICE 14 Claims.

The split skirts of pistons employed in internal combustion engine cylinders frequently develop piston slap. Under long continued inuence of heat and pressure, they may take a permanent set with a diameter less than that of the cylinders. Also, after a period of continued use, the piston and the cylinder will wear circumferentially, so that the diameter of the piston will decrease, while the diameter of the cylinder wall will increase.

It has been proposed to overcome these disadvantages by positively expanding theAskirt of the piston by yieldable means.

One object of the present invention is to provide an improved expanding device which is simple, which may be securely held in place in a standard piston without modifying the piston to any great extent, which is very light so that it does not increase the Weight of the piston, which is adjustable to accommodate for various sized pistons and to compensate for wear, and which is capable of considerable amount of contraction and expansion to follow the contraction and expansion of the piston.

In certain types of piston expanders heretofore used, the expanders have been made to extend across diametrically opposite points in the interior surface of the piston, so that they have added materially to the weight of the piston. Furthermore, these expanders have been applicable only to special types of pistons. It has been proposed to use piston rings extending substantially around the entire internal circumference of the piston skirt, and held in suitable grooves. These grooves have either been machined in the inner surface of the piston, or have been provided in lugs integral with the piston and extending from the internal surface of said piston. It is seen that in order to adapt a piston for receiving an expander of this type, it is necessary to machine a fairly extensive circumferential groove around the internal surface of the piston skirt, or a special type of piston must be employed. My expanding device may be employed in a standard type piston, very slight machining of the piston being required to receive said device. Furthermore, my construction is such that it is applied only at the areas adjoining the slit in the piston skirt, so that the remaining circumferenceof the piston skirt is left unimpaired.

In the accompanying drawings, there is shown for the purpose of illustration, several forms of the device embodying the present invention.

In these drawings Fig. 1 is an end view of a piston showing the expanding device of the present invention mounted in position and before the device is adjusted to expand the skirt.

Fig. 2 is an inside face view of the expanding device on an enlarged scale.

Fig. 3 is a section taken on line 3 3 of Fig. 2, but showing the expanding device in adjusted position.

Fig. 4 is an end view of a piston showing another form of expanding device mounted in position.

Fig. 5 is an inside'face view of the expanding device shown in Fig. 4.

Fig. 6 is a section taken on line 6 6 of Fig. 5.

Fig. 7 is a view of the expanding device taken in the opposite direction from that shown in Fig. 5.

Fig. 8 is a perspective view of the adjusting plate adapted to be used in conjunction with the expanding device shown in Fig. 4.

Fig. ,9 is an inside face v iew of another form of expanding device, and

Fig. 10 is a section taken on line 10 10 of' Fig. 9.

The invention is shown as adapted for use Vwith a common type of aluminum alloy piston 10 having a sleeve or skirt portion 11 open at 85 its lower end. The skirt is shown provided with the usual oppositely disposed bosses 12 apertured to receive a wrist pin, whereby the piston may be attached to a connecting rod. In order to render the piston skirt 11 expansible, said skirt has a longitudinally extending slit 13 extending from the open end of said skirt.

In order to circumferentially expand the skirt against the cylinder wall, there is provided, in the construction shown in Figs. 1 3, an expanding device which includes an expander plate 14 curved and spring tempered to give it inherent resiliency. This expander plate 14 is adapted to bridge across the slit 13 with the convex side of said plate substantially in close proximity to the inner periphery of the skirt 11.

In order to retain the expander plate in position in the inner periphery of the skirt 11, there are riveted or otherwise secured at the yends of said plate pins 15 adapted to pass through apertures 16 in the skirt 11 of the piston, these apertures advantageously extending radially with respect to the piston skirt 11.

Adjustable means are provided for flexing the plate 14, said means in the specific form shown los . of said expander plate, and having end portions frs including an vadjusting plate 17 mounted on the concave side of the expander plate 14, and having a lug 18 at one end thereof offset from the main portion of the plate and extending into a groove or slot 19 formed in the expander plate 14, whereby said adjusting plate is held in position against edgewise movement with respect to said expander plate 14. This adjusting plate 17 is stiffer than the expander plate 14 and is preferably non-resilient. The slot 19 is sufficiently long to permit endwise movement betweenthe adjusting plate 17 and the expander plate 14.

For securing the adjusting plate 17 to the expander plate 14, and for forcing said plates together, there is provided a screw member advantageously in the form of a stud or threaded post 20 flxedly secured at one end -to the central portion of the expander plate 14 by any suitable means, f as for instance riveting, and passing through an aperture 21 in the adjusting plate 17, the outer end of the stud being adapted to extend beyond the plate 17..-to receive a nut 22.

In mounting the device in position, the expander plate 14 with the adjusting plate 17 loosely attached thereto, is inserted in the skirt of the piston, the pins 15 being inserted in the apertures 16 of the skirt. The nut 22 is then turned to move the two plates together, the expander plate 14 being iiexed into straightened Aposition during this operation. 'The operation of turning the nut 22 is a very simple one, its position being such as to easily receive an ordinary wrench.

movement endwise with respect to the expander plate 14.

In order -to prevent accidental turning of the nut 22 when once adjusted,I there isjprovided a locking device which, in the specific form shown, includes a locking plate 23 fastened to the adjusting plate 17 by any suitable means, as for instance rivet 24, and having an aperture 25 to receive the stud 20. This locking plate 23 is provided with a plurality of tongues 26 and is advantageously made of soft steel, 4sgi that these tongues may be easily bent to lock the nut 22 in position, and may be restored into their original positions to permit readjustment of the expanding device.

In the form of expanding device shown in Figs. 4 to 8, the expanding device includes an expander plate 34 curved as shown in Figs. 4 to 7,

and spring tempered to give it inherent resil-.

iency. This expander plate 34 is adapted to be bridged across the slit 13, with the concave side of the plate facing the slit, and preferably has a 4portion stamped or otherwise constructed to form a rectangular recess or groove 35.

For exing the plate 34 there is provided an adjusting plate 36 mounted on the concave side or a pair of oppositely extending lugs 37 adapted 'tri'he engaged in said recess. This plate is stier than the expander plate 34, and is preferably non-resilient. The lugs 37 are slightly narrower than the width of the recess 34, and have rounded corners 38 adapted to slide in the curved base f the' recess. f y

For securing the adjusting plate 36 to the expander plate 34, and for effecting the flexing of The slot 19 cooperates with the lug 18 tol the expander plate, there is advantageously provided a machine screw 40 passing through an aperture 41 in the expander plate 34, and threaded to the adjusting plate 36. To prevent the accidental turning of the screw 40, the head 42 of said screw is advantageously of the iiat type and has a series of corrugations on the conical surface thereof, the end of the aperture 41 being countersunk to receive said head.

In order to secure the expanding device to the piston, said piston is provided with a pair of grooves 44 extending longitudinally of the skirt and disposed at equal distances from the slit 13 on opposite sides thereof. These grooves are suiciently wide to receive the ends of the expander plate 34.

In mounting the device in position, the expander plate 34 with the adjusting plate 36 loosely attached thereto, is inserted in the skirt of the piston, the ends of the expander plate being inserted in the grooves 44. The ends of the expander plate 34 are then urged circumferentially and outwardly by turning the screw 40 to force the adjusting plate closer to said expander plate 34. As this adjusting plate 36 is forced towards the expander plate 34, the ends of the expander plate are exed outwardly to effect the corresponding expansion of the piston skirt 11. As the cylinder piston and the cylinder Walls become worn, the device may be readju'sted by merely turning the screw 40 so as to bring the adjusting plate 36 into close relationship with the expander plate 34. The recess 35 not only serves as a guide channel for the adjusting plate 36 in its adjusting movement, but also serves to hold said plate in position against movement longitudinally of the piston.

In the construction shown in Figs. 9 and 10, there is provided an expander plate 50, the central portion of which is curved in one direction and the ends of which are oifset therefrom and curved in the opposite direction, this expander plate being spring tempered to give it inherent resiliency. The expander plate 50 is adapted to be bridged across the slit 13 with the ends thereof in close proximity to the inner periphery of the skirt 11, and the central portion presenting a concave surface to said slit.

In order to retain the expander plate in position in the inner periphery of the skirt 11, there are riveted or otherwise secured at the ends thereof pins 51 adapted to pass through apertures 51a in the skirt 1l, these apertures advantageously extending' radially with respect to the piston skirt 11.

'Ihe adjusting means for the device includes an adjusting plate 52 mounted on the concave side of the central portion of the expander plate 50, and held in position with respect to the expander plate by means including a nat-headed screw 53 passing through the central portionsuof the adjusting plate 52 and the' expander 50, and having a nut 54 which engages the plate 50. This nut comprises a collar portion 55 passing through the plate 50, and a ange portion 56 forming a shoulder 57 with said collar portion, said shoulder 57 abutting the convex surface of the expander plate 50.

.In order to. move the two expander plates together, the screw 53 is provided with a slot 58 for receiving a suitable turning tool. Means are provided for holding the nut 54 in position while the screw 53 is being turned. For that purpose, the nut 54 has a toothed wheel 60 connected thereto, and engaged by a catch member 61. The catch member 61 is connected to the plate 50 by any suitable means, as for instance rivets 62, and has an offset portion 63 having a V shaped edge 64 which is yieldably urged into engagement with the interdental spaces of the wheel 60, thereby locking the nut 54 in position.

The device shown in Figs. 9 and 10 is operated in a manner similar to that already described with reference to the construction of Figs. 1 to 8, the turning of the screw 53 causing the two plates 50 and 52 to move towards each other so that the pins 51 are moved to expand the piston skirt. If desired, the expander plate 50 may be provided with a groove such as the groove 35 in the constructions of Figs. 4-8 to guide the expander plate 52 in its adjusting movement endwise with respect to the expander plate 50.

My invention provides a simple ard effective device for expanding the skirt of a piston, the specic embodiments of the invention consisting of an expander member having end sections extending at an angle to each other, and an addusting member spanned between said sections, and having its ends spaced from the end sections of said expander member and serving as a fulcrum about which the end sections of said expander member swing as said adjusting member is tted in position. This expanding device is yieldable so as to follow thecontraction and *expansion of the piston.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:-

1. A piston expander including a curved expander plate having inherent resiliency, an

adjusting plate having the ends thereof engag-v ing the concave surface of said expander plate, and means for forcing the adjusting plate towards the central portion of said expander plate, whereby the ends of said adjusting plate force the ends of said expander plate outwardly.

2. A piston expander including a curved resilient expander plate, an adjusting plate disposed on the concave side thereof and having the ends thereof engaging the concave surface of said expander plate, and means for holding said members together and for flexing the central portion of said expander plate towards the adjusting plate to force apart the ends of said expander plate, and including a screw passing through said adjusting plate and said expander plate.

3. A piston comprising an open ended skirt having a slit extending longitudinally from the open end thereof, said skirt being provided in the inside thereof with a pair of grooves extending longitudinally of said skirt, and disposed on opposite sides of said slit, a curved resilient plate having the ends thereof mounted in said grooves to expand said skirt, an adjusting member having the ends thereof engaging the concave side of said curved plate, and meansl for positively forcing said member toward the center portion of the concave side of said curved plate to atten the curvature thereof, and correspondingly expand the piston skirt.

4. A piston expander including an expander member having end sections adapted to engage the inner surface of apiston on opposite sides of a slit therein, an adjusting member between the end sections of said expander member, and having the ends thereof engaging said expander member at points spaced from said end sections, and means acting on said expander member for swinging the ends of said expander member about the ends of said adjusting member as a fulcrum.

5. A piston expander including a curved resilient plate having members projecting from the ends thereof transversely with respect to the general curvature of said plate at said ends, an adjusting plate connected to said expander plate on the concave side thereof, and means for forcing said adjusting plate and said expander plate. together near the central portions of said plates, whereby the ends of said expander plate are urged outwardly.

6. A piston expander including a curved expander plate having inherent resiliency, an adjusting plate connected to said expander plate on the concave side thereof and having the ends thereof engaging the concave surface of said expander plate, a pair of pins projecting from the ends of said expander plate, and means for forcing thev adjusting plate towards the central portion of said expander plate, whereby the ends of said adjusting plate force the ends of said expander plate outwardly.

7. A piston expander including a curved resilient expander plate, an adjusting plate connected to said expander plate on the concave side thereof, and having the ends thereof engaging the concave surface of said expander plate, a stud fixedly connected at one end to one of said plates and passing through the other, a nut threaded onto said stud for forcing the adjusting plate towards the central portion of said expander plate, whereby the ends of said adjusting plate force the ends of said wder plate outwardly, and means adapted to engage the side of said nut for holding said nut in adjusted position.

8. A piston eder including a curved expander plate having inherent resiliency, an adjusting plate connected to said expander plate on the concave side thereof, and having the ends thereof engaging the concave side of said expander plate, a threaded rotatable member, means responsive to the rotation of said rotatable member for forcing the adjusting plate towards the central portion of said expander plate, whereby the ends of said adjusting plate force the ends of said expander plate outwardly, and means carried by one of said plates and adapted to engage said rotatable member to lock said member against accidental turning.

9. A piston expander including an expander plate having the central portion thereof curved, and having the end portions offset from said curved portion, an adjusting plate connected to said expander plate on the concave side thereof, and having the ends thereof engaging the concave surface of the central portionfof said expander plate, and members extending transversely from the end portions of said expander plate, and adapted to be received in apertm'es in the inner surface of a piston skirt.

10. A piston expander including a curved rca silient expander plate provided with an aperture, an adjusting plate adapted to be connected to saidexpander plate on the concave side thereof, and to have one end thereof engaging the walls of said aperture, and means for forcing the .pander plate having an aperture, an usting plate on the concave side of said expander plate and having a lug extending into said aperture, a screw passing through the centerof said ex-a pander plate andsaid adjusting plate, and nut threaded on said screw, said nut and screw being adapted to torce said plates together to iiatte the curvature of the expander plate.

13. combination with a piston having an open-ended skirt and a slit extending longitudinally-of said s from the open end thereof a curved expander plate having inherent resiliency and disposed in the interior oi said piston, with the concave side thereof lacing the axis bf the piston, said expander plate having the ends .to V

thereof held against outward movement in respect to the piston on opposite sides of said slit, an adjusting plate extending across the con cave side of the expander plate, and means lor forcing the central portions. of said plates to gether, whereby the ends' oi ysaid expander plate ,are forced outwardly and the piston expanded.

le. ln combination with a piston ha an openended skirt and a slit extending 1o-I tully of said skirt from the open end thereof, a curved expander plate having inherent re-n siliency and disposed in the interior of said piston, with the concave side thereof facing the central portions of said plates together, A' whereby the ends of said expander plate are and the piston expanded.

urged outwardly CARROIL W. PHASKA.

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